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TT: Fachverband Tiefe Temperaturen

TT 14: Correlated Electrons: Low-Dimensional Systems - Models 2

TT 14.10: Vortrag

Montag, 11. März 2013, 17:30–17:45, H9

Multi-Orbital Effects in Functional Renormalization Group: A Weak-Coupling Study of the Emery model — •Stefan A. Maier and Carsten Honerkamp — Institut für theoretische Festkörperphysik, RWTH Aachen, Germany and JARA - FIT Fundamentals of Future Information Technology

We perform an instability analysis of the Emery three-band model at hole doping and weak coupling within a channel-decomposed functional renormalization group flow proposed in Phys. Rev. B 79, 195125 (2009). In our new approach, momentum dependencies are taken into account with less bias than in the truncated formfactor expansions used previously. Around a generic parameter set, we find a strong competition of antiferromagnetic and d-wave Cooper instabilities with a smooth behavior under a variation of doping and oxygen-oxygen hopping. For increasingly incommensurate ordering tendencies in the magnetic channel, signatures of d-wave Cooper pairing between electrons in non-neighboring unit cells of the direct lattice can be observed. Comparing our results for the Emery model to those obtained for the two-dimensional one-band Hubbard model with effective parameters, we find that, despite considerable qualitative agreement, multi-orbital effects have a significant impact on a quantitative level.